<html>
	<head>
		<meta charset="utf-8">
		<title>jquery</title>
		<script src="jquery-3.2.1.js"></script>
		<script>
			$(function(){
				$("#but").click(function() {
					$("#but").css("background","red");
				});
			})
			
		</script>
	</head>
	<body>
		<input type="button" value="变色" id="but">
	</body>
</html>